Drying leather



prl 5, 1938. w. s. lsl-mw ETAL, 2,113,035

DRYING LEATHER s .L Mmmm @Raw Hamm' .S aw

@gg-f W. S. SHAW ET AL DRYI NG LEATHER April 5, i938.

Filed June l, 1936 2 Sheets-Sheet 2 Patented pr. 5, 1938 DRYING LEATHER William S. Shaw and Harold S. Shaw, Grand Rapids, Mich.

Application June 1, 1936, Serial No. 84,060

Claims.

This inventio-n relates to drying leather and among its objects are the considerable shortening of the time required to complete the drying process as compared with former methods and 5 at the same time improving the quality of the leather.

The saving of time in the drying process is highly important in leather' tanning for different reasons. It reduces the amount of space and equipment necessary to dry a certain number of pieces and permits the turn over in pieces tol be much faster resulting in less investment in the leather in process. The apparatus for accomplishing this invention is comparatively simple and inexpensive and is hereafter more fully described and particularly pointed out in the claims, reference being had to the accompanying drawings, in which,

Fig. l is a sectional plan view of a drying device embodying this invention taken on the line I-I of Fig. 2.

Fig. 2 is a sectional elevation of the same taken on the line 2--2 of Fig. 1.

Fig. 3 is a rear elevation, partly in section,.of one end of the device.

Fig. 4 is a sectional plan on the line 4-4 of Fig. 3, and

Fig. 5 is a perspective View of the portion of the device illustrated in Fig. 3.

Like reference characters refer to like parts in the different figures of the drawings.

The drying device comprises a plurality of chambers IA, IB, 2A and 2B. The number of chambers in the device is not highly important excepting that there must be at least two chambers in a series. The drawings disclose a device having two series of chambers, each series having two chambers as the chambers IA and IB constitute one series and the chambers 2A and 2B constitute the other series. The device is so arranged that all four of the chambers may be used as a single series for consecutive treatment of leather in each.

The chambers have conventional doors 3 which, when closed, are substantially air tight and through which the leather to be dried is passed. Within each of the chambers are racks 4 having suitable conventional means to suspend the p-ieces of leather 5 to be dried and a plurality of the racks 4 are provided in each chamber and a considerable number of pieces of leather 5 are hung thereon in each chamber in closely spaced relationship.

Above and below the leather hanging space in each chamber are located horizontal perforate partitions 6 and I. These partitions may be of any suitable construction such as wire mesh or spaced apart slats and they are for the purpose of forming plenum chambers above them and to accomplish this purpose the total passage space through the partitions is insu'icient to freely pass the air current forced into the chamber abovey them. In other words, an even now of air throughout the drying chamber during the drying process is important and these perforate parl titions having the perforations or passages evenly distributed over the entire area and the partitions extending over the entire area of the respective drying chambers, with the openings through the partitions insufficient, or at least not more than suliicient, to pass the volume of air forced into the chamber above the partitions causes an even distribution of air passing through the parts over its entire area.

It is preferable that the aggregate air passage through a lower partition 'I of achamber be less than the corresponding area in the upper partition 6 of the same chamber. Either of the partitions 6 or 'I in a chamber may be used alone without the other for an approximation of the result obtained when both are used.`

The device is provided with a system of air transfer ducts and passages including air circulating means and air heating means and this air transfer system may be adjusted to variously conduct air between the different chambers of the device.

Each series of chambers is provided with two Vertical ducts, one of which may be termed the intake duct 8 and the other the transfer duct 9. i The intake duct of theseries IA and IB has an inlet opening communicating with the outside atmosphere While the outlet from the transfer duct of the series IA and IB communicates with the inlet opening of the intake duct 8 of the series 2A and 2B by a transfer passage I0.

Each intake duct communicates at its upper end with passages I IA and I IB which respectively communicate with the upper parts of the chambers IA and IB and 2A and 2B. In each intake y duct 8 is a fan I2 which induces an air current in the duct and also a heating element I3 by means of which the air passingl through the duct is heated and additional fans` I4 are'placed at the entrances to the respective chambers. 4

Each transfer duct is in communication at its upper end with both of said passages IIA and IIB and` at its lower end is in communication with passages I5A and I 5B which respectively communicate with the lower parts of the chambers IA and IB and 2A and 2B. The passages I5A and I5B for the chambers IA and IB have an outlet communication with the transfer passage I0 while the passages ISA and I5B for the chambers 2A and 2B have an outlet communication into an exhaust duct I6.

Swinging doors I'I and I8 in the upper passages I IA and I IB direct the passage of the air as desired and in Fig. lthese doors are arranged to direct the air from the intake duct into the upper part of the chambers IA and 2A and to direct the air from the transfer duct into the upper part of the chambers IB and 2B. Swinging doors i9 and 20 in the chambers I5A and I5B at the lower part of the device direct the air as desired from the passages vI5A and ISB into either the transfer duct 9 and the exhaust duct I6 or transfer passage II! and in Fig. 4 the doors I9 and 20 are arranged to direct the air from the lower part of the chamber 2A and the passage ISA Vinto the transfer duct 9 and from the lower part of the chamber 2B and from the passage I5B to the exhaust duct I6.

These doors Il and I8 at the upper part of the structure and I9 and 20 at the lower part of the structure may be swung to reverse positions so that the air will be directed to the opposite chambers and passages than those shown.

A double door 2l, pivoted on a horizontal axis 22 near its center, is provided at the lower end of each intake duct 8 and serves, when in the full line position shown in Fig. 2, to direct the air from the passages IEA and I5B into either the transfer passage I0 or the exhaust duct I6 but when swung to the vertical position shown in dotted lines in Fig. 2 it recirculates the air from the passages I5A and ISB back into the intake duct 8 and thence into the upper part of one of the chambers and is used in this latter position for increasing the humidity of the air circulated for the drying process.-

Operation During the manufacturing of hides into leather it is customary to subject the tanned hides todrying operations. The following describes more fully the operations for drying sole leather, although the dryer may be used successfully and economically on any'drying operation where circulation of conditioned air is required for satis'- factory results on quality and saving of heat units.

A tanned hide must be dried gradually and evenly and although the use of this invention decidedly speeds the drying process the fundamental principles of drying leather must be carefully adhered to. The wet or green leather when rst subjected to the drying process must not be heated to any great extent, the best temperature being approximately F. to '70 F. While at the finish of this rst drying the temperature may be safely increased to F. or more and a1- though the temperature which may be safely used in the finish drying operation may be somewhat higher than those used in the first drying operation at the beginning of the finished drying operation the temperature cannot be as high as may be used at the end of the operation.

likewise in either the first or finish drying operation the air to which the leather is subjected must contain more moisture at the beginning of the operation t-han at the end thereof.

The device illustrated herein, having two series of chambers, each series comprising two chambers used to simultaneously'perform both the rst and finish drying operations, in which case the series of chambers 2A and 2B will be used for the rst drying operation and the series IA and IB will be used for the finish drying operation.

Assuming first that the device is used as two series of chambers in which both the first drying and finished drying operations are performed the green Wet hides are first placed in one of the chambers 2A or 2B and the rolled leather which contains less moisture is placed in one of the chambers IA or IB. Air is then caused to circulate through the device by means of the fans and enters first into the intake duct 8 for the chambers IA and IB and is directed by adjustment of the doors I 1 and I8 at the top and the doors I9 and 20 at the bottom to direct this incoming air, which is heated to the desired temperature by the heating unit I3, into the upper part of the chamber containing the leather fresh from the finishing operation. 'Ihis air current enters the chamber above the perforate partitions 6 and by that partition is caused to be spread evenly over the entire horizontal area of the chamber as itpasses downwardly past the leather hung therein and thence it passes through the lower perforate partition 1, which aids in evenly distributing the air current, and from there it passes outwardly through one of the passages I5A and I5B.

At this stage, while starting the drying operation, the fresh air admitted to the device may be too dry for best results in which case the air is recirculated, by vertically positioning the door 22, back into the intake duct vwhere it again passes through the fans and heater element I3 and the air is continued to be thus recirculated until it has acquiredthe proper amount of moisture content from the leather and until the leather has become sufficiently dry to stand an application of drier air. The door 22 may be adjusted to mid-position in which only a part of the air passing from the lower part of the chamber will be recirculated and the-remainder of the air will be passed into the transfer passage I0 which conducts it into the intake duct 8 for the chambers'ZA and 2B and the series of passageways for these chambers is arranged by means of the doors I'I and I8`and I9 and 20 at upper and lower parts of the device respectively to direct the air thus entering the intake duct into the upper part of the chamber containing the wet green leather and thence downwardly through the perforate partitions 6 and 'I and past the leather and out through the exhaust duct.

It will thus be seen that the fresh dry air is first heated and applied to the wet leather from the finishing operation in one of the chambers IA and IB and if necessary its humidity is increased by recirculation after which the air is conducted to one of the chambers 2A and 2B containing vthe wet green leather. The leather, after the finishing operation, will stand somewhat greater heat and drier air than the fresh green leather and by the'operation thus described the air which is applied to the green leather in one of the chambers 2A and 2Bv has first acquired moisture from the leather in one of the chambers IA and IB before it is applied to the green leather and in so doing it has acquired a considerable moisture content and has also lost some of its heat. If the air, after passing from a chamber IAor IB, is not rwarm enough to be used in the chamber 2A or 2B it is reheated in the /intake duct of the latter chambers by the heating unit I3 therein.

After the leather has progressed approximately half through its drying stage other wet green leather is placed in the other empty chamber 2A or 2B having wet green leather and the other having partially dried green leather, while one of the chambers IA and IB contains wet leather for the iinish drying and the other contains partially dry leather in the finish drying process.

At this stage of the operation the doors I'I and I8 at the upper part of the device and I9 and 20 at the lower part of the device and also the double doors 22 are adjusted so that the fresh incoming air enters the intake duct 8 for the chambers IA and IB and is heated and first directed into the upper part of the chamber having the partially dried leather in the finish drying. It is conducted from the lower part of that chamber into the transfer duct which carries it upward from where it is directed into the upper part of the chamber having the wet leather from the finishing process. From the lower part of that chamber it is directed into the transfer passage I0 which leads it to the intake duct 8 for the chambers 2A and 2B from the upper end of which it is led to the upper part of the chamber having the partially dried green leather. From the lower part of that chamber it is conducted from the transfer duct 8 which leads it upwardly and from there it is directed into the upper part of the chamber having the wet green leather and from the lower part of that chamber it is directed into the exhaust duct.

The aforedescribed process is continued until the leather in one of the chambers in each .group is completely dried at which time the leather in the other chamber of each group is partially dried. At that time the completely dried leather is removed from each of its respective chambers and fresh leather to be subjected to the first drying and finish drying process is placed in the chambers from which the dried leather has been removed. 'Ihen the positions of the doors I1, I8, I9, and 20 are reversed so that the dry heated air will then again be rst conducted to the partially dried leather in the finish drying operation, then to the fresh leather in that operation, then to the partially dried leather in the first drying operation and finallyto the wet green leather.

In this way it will be understood that theY fresh air comparatively dry is first heated to the greatest extent that it is used in the process and applied to the leather in the final stages of the finish drying operation. The air absorbs some moisture from the leather in this stage and also loses some of its heat and is then applied to the leather in the first stage of the finish drying operation where it absorbs more moisture and loses more heat. The air is then applied to the partially dried green leather where more moisture is absorbed and more heat lost and it is finally applied to the wet green leather in a condition in which it has lost substantially al1 of its artificial heat and has considerable moisture content. By thus successively treating the leather in various chambers and in various stages of drying with the same air which automatically changes its condition as it successively passes from one chamber to another and automatically acquires a proper condition, both as to moisture content and heat, to be applied to the leather in the various stages, economy, rapidity and quality are attained.

By means of this device the leather in each chamber may be iirst subjected to a treatment of air in one condition and later subjected to a treatment of air in another condition without moving the leather from one chamber to another but merely by changing the course of the air current through the -device and the condition of the air applied to the leather in each of its stages of drying is definitely controlled and furthermore the air current past the leather is uniform in all parts of the device.

Although the device has been shown and described as having two series of chambers and each series having two chambers the number of series and number of chambers in the series may be varied and modifications have been conceived in which the number of chambers per series is greater than two. In such modifications the same general principle as herein shown is adhered to, namely, that the air is conducted successively from one chamber to another and the succession of chambers to which the air is conducted may be varied at will. Furthermore, it is not essential to the essence of the invention that the device have multiple series but the invention may be embodied and performed in a single series having two or more chambers wherein the number of stages of the drying operation correspond to the number of chambers in the series.

This device results in a great saving of heat units in the leather drying operation because it passes the air successively from one stage of the operation to the next and in each stage it becomes properly conditioned both as to temperature and moisture content for its application to the next stage and the air is not finally exhausted until it has lost practically all of its artificial heat, which has been utilized in the various drying stages. In this way the artificial heat which has been expensively applied to the air is not Wasted but is all used in the various stages of the drying process and in a manner to result in high quality leather.

We claim:

1. A leather drying device comprising, a plurality of chambers, means for inducing an air 'current, means for conducting said air current rst into the top of one chamber of the series, thence from the bottom of said rst chamber into the top of said second chamber of the series and thence for conducting the air out of the bottom of the second chamber of the series and means for adjusting said conducting means in a manner to reverse the succession of the chambers through which the current is conducted.

2. A leather drying device comprising, a plurality of chambers, means for hanging leather in different stages of drying in the respective chambers, means for inducing a current of air into one chamber of the plurality, means for conducting said air current successively from one 'chamber to the other of each of the plurality of chambers and past the leather in each chamber and means for finally exhausting said air from the last charnber of the series, said means for inducing the current of air and said means for conducting the air current introducing the air current into the upper part of each chamber and conducting the air from the lower part of each chamber in a manner to cause a downward movement of the air current past the leather in each chamber.

3. A leather drying device comprising, a plurality of chambers, means for hanging leather in different stages of drying in the respective chambers, means for inducing a current of air into one chamber of the plurality, means for conducting said air current successively from one chamber to the other of each of the plurality of cham.- I5

lbers and past the leather in each chamber and means for nally exhausting said air from the last chamber of the series, means for heating the air introduced into the rst chamber of the series and means for recirculating a part of the air from said first chamber past said heating means and back into said rst chamber.

4. A leather drying device comprising, a plurality of chambers, means for hanging leather in different stages of drying in the respective chambers, means for inducing a current of air into one chamber of the plurality, means for conducting said air current successively from one chamber to the other of eachof the plurality of chambers and past the leather in each chamber and means for nally exhausting said air from the last chamber of the series, a perforate partition of screen in each chamber between the air inlet and the air outlet therein having a series of perforations evenly distributed over its area, the total passage area of said perforations in each partition being insufficient to freely pass the current of air introduced into its respective chamber.

5. A leather drying device comprising, a plurality of chambers arranged in a plurality of series,-

each series having a plurality of chambers, means for circulating air into one of the chambers of one series, means for conducting the air from said chamber to the second chamber of said series, means for' conducting said air current from said second chamber of said series to a chamber of the Second series, means for conducting the air from said chamber of said second series to the second chamber of said second seriesv and means for exhausting the air from said second chamber of said second series, said conducting means adapted to be adjustable to vary the succession of chambers through which the air current is conducted.

WILLIAM S. SHAW. HAROLD S. SHAW. 

